Stabilization of visualization catheters

ABSTRACT

Systems for the stabilization of visualization catheters are described herein which facilitate the deployment and retraction of an imaging hood from a catheter. Such systems may include a deployment catheter and an imaging hood having one or more structural elements which may be integrated or advanced into the hood independently of the hood itself. Moreover, additional features such as rapid exchange ports may be integrated along the hood or along the catheter proximal to the hood to facilitate intravascular procedures and treatments.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. Prov. Pat. App.60/871,415 filed Dec. 21, 2006, which is incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to methods and devices used forstabilizing visualization catheters used to visualize and/or treatregions of tissue within a body. More particularly, the presentinvention relates to methods and apparatus used for structurallystabilizing and/or positioning a hood or barrier or membrane used tointravascularly visualize and/or treat regions of tissue within a body.

BACKGROUND OF THE INVENTION

Conventional devices for accessing and visualizing interior regions of abody lumen are known. For example, ultrasound devices have been used toproduce images from within a body in vivo. Ultrasound has been used bothwith and without contrast agents, which typically enhanceultrasound-derived images.

Other conventional methods have utilized catheters or probes havingposition sensors deployed within the body lumen, such as the interior ofa cardiac chamber. These types of positional sensors are typically usedto determine the movement of a cardiac tissue surface or the electricalactivity within the cardiac tissue. When a sufficient number of pointshave been sampled by the sensors, a “map” of the cardiac tissue may begenerated.

Another conventional device utilizes an inflatable balloon which istypically introduced intravascularly in a deflated state and theninflated against the tissue region to be examined. Imaging is typicallyaccomplished by an optical fiber or other apparatus such as electronicchips for viewing the tissue through the membrane(s) of the inflatedballoon. Moreover, the balloon must generally be inflated for imaging.Other conventional balloons utilize a cavity or depression formed at adistal end of the inflated balloon. This cavity or depression is pressedagainst the tissue to be examined and is flushed with a clear fluid toprovide a clear pathway through the blood.

However, such imaging balloons have many inherent disadvantages. Forinstance, such balloons generally require that the balloon be inflatedto a relatively large size which may undesirably displace surroundingtissue and interfere with fine positioning of the imaging system againstthe tissue. Moreover, the working area created by such inflatableballoons are generally cramped and limited in size. Furthermore,inflated balloons may be susceptible to pressure changes in thesurrounding fluid. For example, if the environment surrounding theinflated balloon undergoes pressure changes, e.g., during systolic anddiastolic pressure cycles in a beating heart, the constant pressurechange may affect the inflated balloon volume and its positioning toproduce unsteady or undesirable conditions for optimal tissue imaging.

Accordingly, these types of imaging modalities are generally unable toprovide desirable images useful for sufficient diagnosis and therapy ofthe endoluminal structure, due in part to factors such as dynamic forcesgenerated by the natural movement of the heart. Moreover, anatomicstructures within the body can occlude or obstruct the image acquisitionprocess. Also, the presence and movement of opaque bodily fluids such asblood generally make in vivo imaging of tissue regions within the heartdifficult.

Other external imaging modalities are also conventionally utilized. Forexample, computed tomography (CT) and magnetic resonance imaging (MRI)are typical modalities which are widely used to obtain images of bodylumens such as the interior chambers of the heart. However, such imagingmodalities fail to provide real-time imaging for intra-operativetherapeutic procedures. Fluoroscopic imaging, for instance, is widelyused to identify anatomic landmarks within the heart and other regionsof the body. However, fluoroscopy fails to provide an accurate image ofthe tissue quality or surface and also fails to provide forinstrumentation for performing tissue manipulation or other therapeuticprocedures upon the visualized tissue regions. In addition, fluoroscopyprovides a shadow of the intervening tissue onto a plate or sensor whenit may be desirable to view the intraluminal surface of the tissue todiagnose pathologies or to perform some form of therapy on it.

Moreover, many of the conventional imaging systems lack the capabilityto provide therapeutic treatments or are difficult to manipulate inproviding effective therapies. For instance, the treatment in apatient's heart for atrial fibrillation is generally made difficult by anumber of factors, such as visualization of the target tissue, access tothe target tissue, and instrument articulation and management, amongstothers.

Conventional catheter techniques and devices, for example such as thosedescribed in U.S. Pat. Nos. 5,895,417; 5,941,845; and 6,129,724, used onthe surface of the heart may be difficult in assuring a transmurallesion or complete blockage of electrical signals. In addition, currentdevices may have difficulty dealing with varying thickness of tissuethrough which a transmural lesion desired.

Conventional accompanying imaging devices, such as fluoroscopy, areunable to detect perpendicular electrode orientation, catheter movementduring the cardiac cycle, and image catheter position throughout lesionformation. Without real-time visualization, it is difficult toreposition devices to another area that requires transmural lesionablation. The absence of real-time visualization also poses the risk ofincorrect placement and ablation of critical structures such as sinusnode tissue which can lead to fatal consequences.

Thus, a tissue imaging system which is able to provide real-time in vivoaccess to and images of tissue regions within body lumens such as theheart through opaque media such as blood and which also providesinstruments for therapeutic procedures are desirable.

SUMMARY OF THE INVENTION

The tissue-imaging apparatus described relates to variations of a deviceand/or method to provide real-time images in vivo of tissue regionswithin a body lumen such as a heart, which is filled with blood flowingdynamically therethrough. Such an apparatus may be utilized for manyprocedures, e.g., mitral valvuloplasty, left atrial appendage closure,arrhythmia ablation, transeptal access and patent foramen ovale closureamong other procedures. Further details of such a visualization catheterand methods of use are shown and described in U.S. Pat. Pub.2006/0184048 A1, which is incorporated herein by reference in itsentirety.

A tissue imaging and manipulation apparatus that may be utilized forprocedures within a body lumen, such as the heart, in whichvisualization of the surrounding tissue is made difficult, if notimpossible, by medium contained within the lumen such as blood, isdescribed below. Generally, such a tissue imaging and manipulationapparatus comprises an optional delivery catheter or sheath throughwhich a deployment catheter and imaging hood may be advanced forplacement against or adjacent to the tissue to be imaged.

The deployment catheter may define a fluid delivery lumen therethroughas well as an imaging lumen within which an optical imaging fiber orelectronic imaging assembly may be disposed for imaging tissue. Whendeployed, the imaging hood may be expanded into any number of shapes,e.g., cylindrical, conical as shown, semi-spherical, etc., provided thatan open area or field is defined by the imaging hood. The open area isthe area within which the tissue region of interest may be imaged. Theimaging hood may also define an atraumatic contact lip or edge forplacement or abutment against the tissue region of interest. Moreover,the distal end of the deployment catheter or separate manipulatablecatheters may be articulated through various controlling mechanisms suchas push-pull wires manually or via computer control

In operation, after the imaging hood has been deployed, fluid may bepumped at a positive pressure through the fluid delivery lumen until thefluid fills the open area completely and displaces any blood from withinthe open area. The fluid may comprise any biocompatible fluid, e.g.,saline, water, plasma, Fluorinert™, etc., which is sufficientlytransparent to allow for relatively undistorted visualization throughthe fluid. The fluid may be pumped continuously or intermittently toallow for image capture by an optional processor which may be incommunication with the assembly.

To structurally support the hood in its deployed configuration during aprocedure, a number of structural members may be incorporated into thehood. For example, a circumferential frame or scaffold may be advancedand/or retracted along or within the hood to provide structural supportwhen expanded to provide circumferential or hoop strength, especially atthe distal circumference of hood where the frame is positioned. Thecircumferential or hoop strength provided by the support frame may givethe hood additional resistance from collapsing inwardly or from closingup at the distal end, particularly when submerged in a body lumen withfluids such as blood, or when submerged in a body lumen having arelatively high fluid flow, such as the atrial or ventricular chambersof the heart and particularly near areas such as the pulmonary veinostia, the mitral valve, or the tricuspid valve, etc.

Other variations may utilize structural elements or ligaments placed orintegrated along the hood. Moreover, features such as rapid exchangeports may be integrated along the hood itself or along the catheterproximal to the hood to facilitate intravascular procedures andtreatment of the tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a side view of one variation of a tissue imaging apparatusduring deployment from a sheath or delivery catheter.

FIG. 1B shows the deployed tissue imaging apparatus of FIG. 1A having anoptionally expandable hood or sheath attached to an imaging and/ordiagnostic catheter.

FIG. 1C shows an end view of a deployed imaging apparatus.

FIGS. 1D to 1F show the apparatus of FIGS. 1A to 1C with an additionallumen, e.g., for passage of a guidewire therethrough.

FIGS. 2A and 2B show one example of a deployed tissue imager positionedagainst or adjacent to the tissue to be imaged and a flow of fluid, suchas saline, displacing blood from within the expandable hood.

FIG. 3A shows an articulatable imaging assembly which may be manipulatedvia push-pull wires or by computer control.

FIGS. 3B and 3C show steerable instruments, respectively, where anarticulatable delivery catheter may be steered within the imaging hoodor a distal portion of the deployment catheter itself may be steered.

FIGS. 4A to 4C show side and cross-sectional end views, respectively, ofanother variation having an off-axis imaging capability.

FIGS. 4D and 4E show examples of various visualization imagers which maybe utilized within or along the imaging hood.

FIG. 5 shows an illustrative view of an example of a tissue imageradvanced intravascularly within a heart for imaging tissue regionswithin an atrial chamber.

FIGS. 6A to 6C illustrate deployment catheters having one or moreoptional inflatable balloons or anchors for stabilizing the deviceduring a procedure.

FIGS. 7A and 7B illustrate a variation of an anchoring mechanism such asa helical tissue piercing device for temporarily stabilizing the imaginghood relative to a tissue surface.

FIG. 7C shows another variation for anchoring the imaging hood havingone or more tubular support members integrated with the imaging hood;each support members may define a lumen therethrough for advancing ahelical tissue anchor within.

FIG. 8A shows an illustrative example of one variation of how a tissueimager may be utilized with an imaging device.

FIG. 8B shows a further illustration of a hand-held variation of thefluid delivery and tissue manipulation system.

FIGS. 9A to 9C illustrate an example of capturing several images of thetissue at multiple regions.

FIGS. 10A and 10B show charts illustrating how fluid pressure within theimaging hood may be coordinated with the surrounding blood pressure; thefluid pressure in the imaging hood may be coordinated with the bloodpressure or it may be regulated based upon pressure feedback from theblood.

FIGS. 11A to 11C illustrate perspective views of one variation of avisualization catheter having a collapsible support frame which providesstructural support to the hood being retracted into the deploymentcatheter.

FIGS. 12A and 12B show perspective views of the hood being retractedinto the catheter once the circumferential support frame has beenretracted.

FIGS. 13A and 13B show partial cross-sectional side views illustratingthe collapsed and fully retracted hood within the catheter correspondingto FIGS. 12A and 12B.

FIGS. 14A and 14B show side and perspective views, respectively, ofanother variation of a hood having circumferentially and axiallyoriented structural linings or “ligaments” providing circumferential andaxial strength to the hood.

FIG. 15 shows a perspective view of another variation of a visualizationcatheter having a rapid exchange feature integrated along the hood whichalso incorporates several projections for adhering the hood temporarilyto tissue.

FIGS. 16A and 16B show side and perspective views, respectively, ofanother variation of an optional rapid exchange feature where aguidewire opening may be defined along a portion of the hood.

FIGS. 17A and 17B show side and perspective views, respectively, ofanother variation having the rapid exchange feature incorporated alongthe hood through which an ablation probe or other instrument may bepositioned.

FIGS. 18A and 18B show side and perspective views, respectively, of yetanother variation of an optional rapid exchange feature where a rapidexchange side port is defined along the catheter proximal to the hoodfor the direct passage of any number of instruments therethrough.

DETAILED DESCRIPTION OF THE INVENTION

A tissue-imaging and manipulation apparatus described below is able toprovide real-time images in vivo of tissue regions within a body lumensuch as a heart, which is filled with blood flowing dynamicallytherethrough and is also able to provide intravascular tools andinstruments for performing various procedures upon the imaged tissueregions. Such an apparatus may be utilized for many procedures, e.g.,facilitating transeptal access to the left atrium, cannulating thecoronary sinus, diagnosis of valve regurgitation/stenosis,valvuloplasty, atrial appendage closure, arrhythmogenic focus ablation,among other procedures. Further examples of tissue visualizationcatheters which may be utilized are shown and described in furtherdetail in U.S. patent application Ser. No. 11/259,498 filed Oct. 25,2005, which has been incorporated hereinabove by reference in itsentirety.

One variation of a tissue access and imaging apparatus is shown in thedetail perspective views of FIGS. 1A to 1C. As shown in FIG. 1A, tissueimaging and manipulation assembly 10 may be delivered intravascularlythrough the patient's body in a low-profile configuration via a deliverycatheter or sheath 14. In the case of treating tissue, such as themitral valve located at the outflow tract of the left atrium of theheart, it is generally desirable to enter or access the left atriumwhile minimizing trauma to the patient. To non-operatively effect suchaccess, one conventional approach involves puncturing the intra-atrialseptum from the right atrial chamber to the left atrial chamber in aprocedure commonly called a transeptal procedure or septostomy. Forprocedures such as percutaneous valve repair and replacement, transeptalaccess to the left atrial chamber of the heart may allow for largerdevices to be introduced into the venous system than can generally beintroduced percutaneously into the arterial system.

When the imaging and manipulation assembly 10 is ready to be utilizedfor imaging tissue, imaging hood 12 may be advanced relative to catheter14 and deployed from a distal opening of catheter 14, as shown by thearrow. Upon deployment, imaging hood 12 may be unconstrained to expandor open into a deployed imaging configuration, as shown in FIG. 1B.Imaging hood 12 may be fabricated from a variety of pliable orconformable biocompatible material including but not limited to, e.g.,polymeric, plastic, or woven materials. One example of a woven materialis Kevlar® (E.I. du Pont de Nemours, Wilmington, Del.), which is anaramid and which can be made into thin, e.g., less than 0.001 in.,materials which maintain enough integrity for such applicationsdescribed herein. Moreover, the imaging hood 12 may be fabricated from atranslucent or opaque material and in a variety of different colors tooptimize or attenuate any reflected lighting from surrounding fluids orstructures, i.e., anatomical or mechanical structures or instruments. Ineither case, imaging hood 12 may be fabricated into a uniform structureor a scaffold-supported structure, in which case a scaffold made of ashape memory alloy, such as Nitinol, or a spring steel, or plastic,etc., may be fabricated and covered with the polymeric, plastic, orwoven material. Hence, imaging hood 12 may comprise any of a widevariety of barriers or membrane structures, as may generally be used tolocalize displacement of blood or the like from a selected volume of abody lumen or heart chamber. In exemplary embodiments, a volume withinan inner surface 13 of imaging hood 12 will be significantly less than avolume of the hood 12 between inner surface 13 and outer surface 11.

Imaging hood 12 may be attached at interface 24 to a deployment catheter16 which may be translated independently of deployment catheter orsheath 14. Attachment of interface 24 may be accomplished through anynumber of conventional methods. Deployment catheter 16 may define afluid delivery lumen 18 as well as an imaging lumen 20 within which anoptical imaging fiber or assembly may be disposed for imaging tissue.When deployed, imaging hood 12 may expand into any number of shapes,e.g., cylindrical, conical as shown, semi-spherical, etc., provided thatan open area or field 26 is defined by imaging hood 12. The open area 26is the area within which the tissue region of interest may be imaged.Imaging hood 12 may also define an atraumatic contact lip or edge 22 forplacement or abutment against the tissue region of interest. Moreover,the diameter of imaging hood 12 at its maximum fully deployed diameter,e.g., at contact lip or edge 22, is typically greater relative to adiameter of the deployment catheter 16 (although a diameter of contactlip or edge 22 may be made to have a smaller or equal diameter ofdeployment catheter 16). For instance, the contact edge diameter mayrange anywhere from 1 to 5 times (or even greater, as practicable) adiameter of deployment catheter 16. FIG. 1C shows an end view of theimaging hood 12 in its deployed configuration. Also shown are thecontact lip or edge 22 and fluid delivery lumen 18 and imaging lumen 20.

The imaging and manipulation assembly 10 may additionally define aguidewire lumen therethrough, e.g., a concentric or eccentric lumen, asshown in the side and end views, respectively, of FIGS. 1D to 1F. Thedeployment catheter 16 may define guidewire lumen 19 for facilitatingthe passage of the system over or along a guidewire 17, which may beadvanced intravascularly within a body lumen. The deployment catheter 16may then be advanced over the guidewire 17, as generally known in theart.

In operation, after imaging hood 12 has been deployed, as in FIG. 1B,and desirably positioned against the tissue region to be imaged alongcontact edge 22, the displacing fluid may be pumped at positive pressurethrough fluid delivery lumen 18 until the fluid fills open area 26completely and displaces any fluid 28 from within open area 26. Thedisplacing fluid flow may be laminarized to improve its clearing effectand to help prevent blood from re-entering the imaging hood 12.Alternatively, fluid flow may be started before the deployment takesplace. The displacing fluid, also described herein as imaging fluid, maycomprise any biocompatible fluid, e.g., saline, water, plasma, etc.,which is sufficiently transparent to allow for relatively undistortedvisualization through the fluid. Alternatively or additionally, anynumber of therapeutic drugs may be suspended within the fluid or maycomprise the fluid itself which is pumped into open area 26 and which issubsequently passed into and through the heart and the patient body.

As seen in the example of FIGS. 2A and 2B, deployment catheter 16 may bemanipulated to position deployed imaging hood 12 against or near theunderlying tissue region of interest to be imaged, in this example aportion of annulus A of mitral valve MV within the left atrial chamber.As the surrounding blood 30 flows around imaging hood 12 and within openarea 26 defined within imaging hood 12, as seen in FIG. 2A, theunderlying annulus A is obstructed by the opaque blood 30 and isdifficult to view through the imaging lumen 20. The translucent fluid28, such as saline, may then be pumped through fluid delivery lumen 18,intermittently or continuously, until the blood 30 is at leastpartially, and preferably completely, displaced from within open area 26by fluid 28, as shown in FIG. 2B.

Although contact edge 22 need not directly contact the underlyingtissue, it is at least preferably brought into close proximity to thetissue such that the flow of clear fluid 28 from open area 26 may bemaintained to inhibit significant backflow of blood 30 back into openarea 26. Contact edge 22 may also be made of a soft elastomeric materialsuch as certain soil grades of silicone or polyurethane, as typicallyknown, to help contact edge 22 conform to an uneven or rough underlyinganatomical tissue surface. Once the blood 30 has been displaced fromimaging hood 12, an image may then be viewed of the underlying tissuethrough the clear fluid 30. This image may then be recorded or availablefor real-time viewing for performing a therapeutic procedure. Thepositive flow of fluid 28 may be maintained continuously to provide forclear viewing of the underlying tissue. Alternatively, the fluid 28 maybe pumped temporarily or sporadically only until a clear view of thetissue is available to be imaged and recorded, at which point the fluidflow 28 may cease and blood 30 may be allowed to seep or flow back intoimaging hood 12. This process may be repeated a number of times at thesame tissue region or at multiple tissue regions.

In desirably positioning the assembly at various regions within thepatient body, a number of articular ion and manipulation controls may beutilized. For example, as shown in the articulatable imaging assembly 40in FIG. 3A, one or more push-pull wires 42 may be routed throughdeployment catheter 16 for steering the distal end portion of the devicein various directions 46 to desirably position the imaging hood 12adjacent to a region of tissue to be visualized. Depending upon thepositioning and the number of push-pull wires 42 utilized, deploymentcatheter 16 and imaging hood 12 may be articulated into any number ofconfigurations 44. The push-pull wire or wires 42 may be articulated viatheir proximal ends from outside the patient body manually utilizing oneor more controls. Alternatively, deployment catheter 16 may bearticulated by computer control, as further described below.

Additionally or alternatively, an articulatable delivery catheter 48,which may be articulated via one or more push-pull wires and having animaging lumen and one or more working lumens, may be delivered throughthe deployment catheter 16 and into imaging hood 12. With a distalportion of articulatable delivery catheter 48 within imaging hood 12,the clear displacing fluid may be pumped through delivery catheter 48 ordeployment catheter 16 to clear the field within imaging hood 12. Asshown in FIG. 3B, the articulatable delivery catheter 48 may bearticulated within the imaging hood to obtain a better image of tissueadjacent to the imaging hood 12. Moreover, articulatable deliverycatheter 48 may be articulated to direct an instrument or tool passedthrough the catheter 48, as described in detail below, to specific areasof tissue imaged through imaging hood 12 without having to repositiondeployment catheter 16 and re-clear the imaging field within hood 12.

Alternatively, rather than passing an articulatable delivery catheter 48through the deployment catheter 16, a distal portion of the deploymentcatheter 16 itself may comprise a distal end 49 which is articulatablewithin imaging hood 12, as shown in FIG. 3C. Directed imaging,instrument delivery, etc., may be accomplished directly through one ormore lumens within deployment catheter 16 to specific regions of theunderlying tissue imaged within imaging hood 12.

Visualization within the imaging hood 12 may be accomplished through animaging lumen 20 defined through deployment catheter 16, as describedabove. In such a configuration, visualization is available in astraight-line manner, i.e., images are generated from the field distallyalong a longitudinal axis defined by the deployment catheter 16.Alternatively or additionally, an articulatable imaging assembly havinga pivotable support member 50 may be connected to, mounted to, orotherwise passed through deployment catheter 16 to provide forvisualization off-axis relative to the longitudinal axis defined bydeployment catheter 16, as shown in FIG. 4A. Support member 50 may havean imaging element 52, e.g., a CCD or CMOS imager or optical fiber,attached at its distal end with its proximal end connected to deploymentcatheter 16 via a pivoting connection 54.

If one or more optical fibers are utilized for imaging, the opticalfibers 58 may be passed through deployment catheter 16, as shown in thecross-section of FIG. 4B, and routed through the support member 50. Theuse of optical fibers 58 may provide for increased diameter sizes of theone or several lumens 56 through deployment catheter 16 for the passageof diagnostic and/or therapeutic tools therethrough. Alternatively,electronic chips, such as a charge coupled device (CCD) or a CMOSimager, which are typically known, may be utilized in place of theoptical fibers 58, in which case the electronic imager may be positionedin the distal portion of the deployment catheter 16 with electric wiresbeing routed proximally through the deployment catheter 16.Alternatively, the electronic imagers may be wirelessly coupled to areceiver for the wireless transmission of images. Additional opticalfibers or light emitting diodes (LEDs) can be used to provide lightingfor the image or operative theater, as described below in furtherdetail. Support member 50 may be pivoted via connection 54 such that themember 50 can be positioned in a low-profile configuration withinchannel or groove 60 defined in a distal portion of catheter 16, asshown in the cross-section of FIG. 4C. During intravascular delivery ofdeployment catheter 16 through the patient body, support member 50 canbe positioned within channel or groove 60 with imaging hood 12 also inits low-profile configuration. During visualization, imaging hood 12 maybe expanded into its deployed configuration and support member 50 may bedeployed into its off-axis configuration for imaging the tissue adjacentto hood 12, as in FIG. 4A. Other configurations for support member 50for off-axis visualization may be utilized, as desired.

FIG. 4D shows a partial cross-sectional view of an example where one ormore optical fiber bundles 62 may be positioned within the catheter andwithin imaging hood 12 to provide direct in-line imaging of the openarea within hood 12. FIG. 4E shows another example where an imagingelement 64 (e.g., CCD or CMOS electronic imager) may be placed along aninterior surface of imaging hood 12 to provide imaging of the open areasuch that the imaging element 64 is off-axis relative to a longitudinalaxis of the hood 12. The off-axis position of element 64 may provide fordirect visualization and uninhibited access by instruments from thecatheter to the underlying tissue during treatment.

FIG. 5 shows an illustrative cross-sectional view of a heart H havingtissue regions of interest being viewed via an imaging assembly 10. Inthis example, delivery catheter assembly 70 may be introducedpercutaneously into the patient's vasculature and advanced through thesuperior vena cava SVC and into the right atrium RA. The deliverycatheter or sheath 72 may be articulated through the atrial septum ASand into the left atrium LA for viewing or treating the tissue, e.g.,the annulus A, surrounding the mitral valve MV. As shown, deploymentcatheter 16 and imaging hood 12 may be advanced out of delivery catheter72 and brought into contact or in proximity to the tissue region ofinterest. In other examples, delivery catheter assembly 70 may beadvanced through the inferior vena cava IVC, if so desired. Moreover,other regions of the heart H, e.g., the right ventricle RV or leftventricle, LV, may also be accessed and imaged or treated by imagingassembly 10.

In accessing regions of the heart H or other parts of the body, thedelivery catheter or sheath 14 may comprise a conventionalintra-vascular catheter or an endoluminal delivery device.Alternatively, robotically-controlled delivery catheters may also beoptionally utilized with the imaging assembly described herein, in whichcase a computer-controller 74 may be used to control the articulationand positioning of the delivery catheter 14. An example of arobotically-controlled delivery catheter which may be utilized isdescribed in further detail in US Pat. Pub. 2002/0087169 A1 to Brock etal. entitled “Flexible Instrument”, which is incorporated herein byreference in its entirety. Other robotically-controlled deliverycatheters manufactured by Hansen Medical, Inc. (Mountain View, Calif.)may also be utilized with the delivery catheter 14.

To facilitate stabilization of the deployment catheter 16 during aprocedure, one or more inflatable balloons or anchors 76 may bepositioned along the length of catheter 16, as shown in FIG. 6A. Forexample, when utilizing a transeptal approach across the atrial septumAS into the left atrium LA, the inflatable balloons 76 may be inflatedfrom a low-profile into their expanded configuration to temporarilyanchor or stabilize the catheter 16 position relative to the heart H.FIG. 6B shows a first balloon 78 inflated while FIG. 6C also shows asecond balloon 80 inflated proximal to the first balloon 78. In such aconfiguration, the septal wall AS may be wedged or sandwiched betweenthe balloons 78; 80 to temporarily stabilize the catheter 16 and imaginghood 12. A single balloon 78 or both balloons 78, 80 may be used. Otheralternatives may utilize expandable mesh members, malecots, or any othertemporary expandable structure. After a procedure has been accomplished,the balloon assembly 76 may be deflated or re-configured into alow-profile for removal of the deployment catheter 16.

To further stabilize a position of the imaging hood 12 relative to atissue surface to be imaged, various anchoring mechanisms may beoptionally employed for temporarily holding the imaging hood 12 againstthe tissue. Such anchoring mechanisms may be particularly useful forimaging tissue which is subject to movement, e.g., when imaging tissuewithin the chambers of a beating heart. A tool delivery catheter 82having at least one instrument lumen and an optional visualization lumenmay be delivered through deployment catheter 16 and into an expandedimaging hood 12. As the imaging hood 12 is brought into contact againsta tissue surface T to be examined, anchoring mechanisms such as ahelical tissue piercing device 84 may be passed through the tooldelivery catheter 82, as shown in FIG. 7A, and into imaging hood 12.

The helical tissue engaging device 84 may be torqued from its proximalend outside the patient body to temporarily anchor itself into theunderlying tissue surface T. Once embedded within the tissue T, thehelical tissue engaging device 84 may be pulled proximally relative todeployment catheter 16 while the deployment catheter 16 and imaging hood12 are pushed distally, as indicated by the arrows in FIG. 7B, to gentlyforce the contact edge or lip 22 of imaging hood against the tissue T.The positioning of the tissue engaging device 84 may be lockedtemporarily relative to the deployment catheter 16 to ensure securepositioning of the imaging hood 12 during a diagnostic or therapeuticprocedure within the imaging hood 12. After a procedure, tissue engagingdevice 84 may be disengaged from the tissue by torquing its proximal endin the opposite direction to remove the anchor from the tissue T and thedeployment catheter 16 may be repositioned to another region of tissuewhere the anchoring process may be repeated or removed from the patientbody. The tissue engaging device 84 may also be constructed from otherknown tissue engaging devices such as vacuum-assisted engagement orgrasper-assisted engagement tools, among others.

Although a helical anchor 84 is shown, this is intended to beillustrative and other types of temporary anchors may be utilized, e.g.,hooked or barbed anchors, graspers, etc. Moreover, the tool deliverycatheter 82 may be omitted entirely and the anchoring device may bedelivered directly through a lumen defined through the deploymentcatheter 16.

In another variation where the tool delivery catheter 82 may be omittedentirely to temporarily anchor imaging hood 12, FIG. 7C shows an imaginghood 12 having one or more tubular support members 86, e.g., foursupport members 86 as shown, integrated with the imaging hood 12. Thetubular support members 86 may define lumens therethrough each havinghelical tissue engaging devices 88 positioned within. When an expandedimaging hood 12 is to be temporarily anchored to the tissue, the helicaltissue engaging devices 88 may be urged distally to extend from imaginghood 12 and each may be torqued from its proximal end to engage theunderlying tissue T. Each of the helical tissue engaging devices 88 maybe advanced through the length of deployment catheter 16 or they may bepositioned within tubular support members 86 during the delivery anddeployment of imaging hood 12. Once the procedure within imaging hood 12is finished, each of the tissue engaging devices 88 may be disengagedfrom the tissue and the imaging hood 12 may be repositioned to anotherregion of tissue or removed from the patient body.

An illustrative example is shown in FIG. 8A of a tissue imaging assemblyconnected to a fluid delivery system 90 and to an optional processor 98and image recorder and/or viewer 100. The fluid delivery system 90 maygenerally comprise a pump 92 and an optional valve 94 for controllingthe flow rate of the fluid into the system. A fluid reservoir 96,fluidly connected to pump 92, may hold the fluid to be pumped throughimaging hood 12. An optional central processing unit or processor 98 maybe in electrical communication with fluid delivery system 90 forcontrolling flow parameters such as the flow rate and/or velocity of thepumped fluid. The processor 98 may also be in electrical communicationwith an image recorder and/or viewer 100 for directly viewing the imagesof tissue received from within imaging hood 12. Imager recorder and/orviewer 100 may also be used not only to record the image but also thelocation of the viewed tissue region, if so desired.

Optionally, processor 98 may also be utilized to coordinate the fluidflow and the image capture. For instance, processor 98 may be programmedto provide for fluid flow from reservoir 96 until the tissue area hasbeen displaced of blood to obtain a clear image. Once the image has beendetermined to be sufficiently clear, either visually by a practitioneror by computer, an image of the tissue may be captured automatically byrecorder 100 and pump 92 may be automatically stopped or slowed byprocessor 98 to cease the fluid flow into the patient. Other variationsfor fluid delivery and image capture are, of course, possible and theaforementioned configuration is intended only to be illustrative and notlimiting.

FIG. 8B shows a further illustration of a hand-held variation of thefluid delivery and tissue manipulation system 110. In this variation,system 110 may have a housing or handle assembly 112 which can be heldor manipulated by the physician from outside the patient body. The fluidreservoir 114, shown in this variation as a syringe, can be fluidlycoupled to the handle assembly 112 and actuated via a pumping mechanism116, e.g., lead screw. Fluid reservoir 114 may be a simple reservoirseparated from the handle assembly 112 and fluidly coupled to handleassembly 112 via one or more tubes. The fluid flow rate and othermechanisms may be metered by the electronic controller 118.

Deployment of imaging hood 12 may be actuated by a hood deploymentswitch 120 located on the handle assembly 112 while dispensation of thefluid from reservoir 114 may be actuated by a fluid deployment switch122, which can be electrically coupled to the controller 118. Controller118 may also be electrically coupled to a wired or wireless antenna 124optionally integrated with the handle assembly 112, as shown in thefigure. The wireless antenna 124 can be used to wirelessly transmitimages captured from the imaging hood 12 to a receiver, e.g., viaBluetooth® wireless technology (Bluetooth SIG, Inc., Bellevue, Wash.),RF, etc., for viewing on a monitor 128 or for recording for laterviewing.

Articulation control of the deployment catheter 16, or a deliverycatheter or sheath 14 through which the deployment catheter 16 may bedelivered, may be accomplished by computer control, as described above,in which case an additional controller may be utilized with handleassembly 112. In the case of manual articulation, handle assembly 112may incorporate one or more articulation controls 126 for manualmanipulation of the position of deployment catheter 16. Handle assembly112 may also define one or more instrument ports 130 through which anumber of intravascular tools may be passed for tissue manipulation andtreatment within imaging hood 12, as described further below.Furthermore, in certain procedures, fluid or debris may be sucked intoimaging hood 12 for evacuation from the patient body by optionallyfluidly coupling a suction pump 132 to handle assembly 112 or directlyto deployment catheter 16.

As described above, fluid may be pumped continuously into imaging hood12 to provide for clear viewing of the underlying tissue. Alternatively,fluid may be pumped temporarily or sporadically only until a clear viewof the tissue is available to be imaged and recorded, at which point thefluid flow may cease and the blood may be allowed to seep or flow backinto imaging hood 12. FIGS. 9A to 9C illustrate an example of capturingseveral images of the tissue at multiple regions. Deployment catheter 16may be desirably positioned and imaging hood 12 deployed and broughtinto position against a region of tissue to be imaged, in this examplethe tissue surrounding a mitral valve MV within the left atrium of apatient's heart. The imaging hood 12 may be optionally anchored to thetissue, as described above, and then cleared by pumping the imagingfluid into the hood 12. Once sufficiently clear, the tissue may bevisualized and the image captured by control electronics 118. The firstcaptured image 140 may be stored and/or transmitted wirelessly 124 to amonitor 128 for viewing by the physician, as shown in FIG. 9A.

The deployment catheter 16 may be then repositioned to an adjacentportion of mitral valve MV, as shown in FIG. 9B, where the process maybe repeated to capture a second image 142 for viewing and/or recording.The deployment catheter 16 may again be repositioned to another regionof tissue, as shown in FIG. 9C, where a third image 144 may be capturedfor viewing and/or recording. This procedure may be repeated as manytimes as necessary for capturing a comprehensive image of the tissuesurrounding mitral valve MV, or any other tissue region. When thedeployment catheter 16 and imaging hood 12 is repositioned from tissueregion to tissue region, the pump may be stopped during positioning andblood or surrounding fluid may be allowed to enter within imaging hood12 until the tissue is to be imaged, where the imaging hood 12 may becleared, as above.

As mentioned above, when the imaging hood 12 is cleared by pumping theimaging fluid within for clearing the blood or other bodily fluid, thefluid may be pumped continuously to maintain the imaging fluid withinthe hood 12 at a positive pressure or it may be pumped under computercontrol for slowing or stopping the fluid flow into the hood 12 upondetection of various parameters or until a clear image of the underlyingtissue is obtained. The control electronics 118 may also be programmedto coordinate the fluid flow into the imaging hood 12 with variousphysical parameters to maintain a clear image within imaging hood 12.

One example is shown in FIG. 10A which shows a chart 150 illustratinghow fluid pressure within the imaging hood 12 may be coordinated withthe surrounding blood pressure. Chart 150 shows the cyclical bloodpressure 156 alternating between diastolic pressure 152 and systolicpressure 154 over time T due to the beating motion of the patient heart.The fluid pressure of the imaging fluid, indicated by plot 160, withinimaging hood 12 may be automatically timed to correspond to the bloodpressure changes 160 such that an increased pressure is maintainedwithin imaging hood 12 which is consistently above the blood pressure156 by a slight increase ΔP, as illustrated by the pressure differenceat the peak systolic pressure 158. This pressure difference, ΔP, may bemaintained within imaging hood 12 over the pressure variance of thesurrounding blood pressure to maintain a positive imaging fluid pressurewithin imaging hood 12 to maintain a clear view of the underlyingtissue. One benefit of maintaining a constant ΔP is a constant flow andmaintenance of a clear field.

FIG. 10B shows a chart 162 illustrating another variation formaintaining a clear view of the underlying tissue where one or moresensors within the imaging hood 12, as described in further detailbelow, may be configured to sense pressure changes within the imaginghood 12 and to correspondingly increase the imaging fluid pressurewithin imaging hood 12. This may result in a time delay, ΔT, asillustrated by the shifted fluid pressure 160 relative to the cyclingblood pressure 156, although the time delays ΔT may be negligible inmaintaining the clear image of the underlying tissue. Predictivesoftware algorithms can also be used to substantially eliminate thistime delay by predicting when the next pressure wave peak will arriveand by increasing the pressure ahead of the pressure wave's arrival byan amount of time equal to the aforementioned time delay to essentiallycancel the time delay out.

The variations in fluid pressure within imaging hood 12 may beaccomplished in part due to the nature of imaging hood 12. An inflatableballoon, which is conventionally utilized for imaging tissue, may beaffected by the surrounding blood pressure changes. On the other hand,an imaging hood 12 retains a constant volume therewithin and isstructurally unaffected by the surrounding blood pressure changes, thusallowing for pressure increases therewithin. The material that hood 12is made from may also contribute to the manner in which the pressure ismodulated within this hood 12. A stiffer hood material, such as highdurometer polyurethane or Nylon, may facilitate the maintaining of anopen hood when deployed. On the other hand, a relatively lower durometeror softer material, such as a low durometer PVC or polyurethane, maycollapse from the surrounding fluid pressure and may not adequatelymaintain a deployed or expanded hood.

To further structurally support the hood 12 in its deployedconfiguration, a number of structural members may be incorporated intothe hood 12. An example is illustrated in the perspective views of FIGS.11A to 11C, which show a circumferential scaffold or frame 170 that maybe advanced and/or retracted along or within hood 12 to providestructural support when hood 12 is expanded to support the hood 12 andprovide circumferential or hoop strength, especially at the distalcircumference of hood 12 where frame 170 is positioned. Thecircumferential or hoop strength provided by the support frame 170 maygive hood 12 additional resistance from collapsing inwardly or fromclosing up at the distal end, particularly when submerged in a bodylumen with fluids such as blood, or when submerged in a body lumenhaving a relatively high fluid flow, such as the atrial or ventricularchambers of the heart and particularly near areas such as the pulmonaryvein ostia, the mitral valve, or the tricuspid valve, etc.

The support frame 170 can be made from shape memory alloy wire, such asNitinol, that is pre-shaped into a circular structure, e.g., a ring,which is connected to a single strut or frame support member 172extending perpendicularly to the ring. FIG. 11A shows hood 12 havingcircumferential frame 170 positioned around the contact lip or edge ofthe hood 12 with frame support member 172 connected to frame 170 andextending proximally along or within hood 12 and through catheter 16.Hood 12 may define an annular channel 174 between an inner and outerlayer of material (such as C-flex, chronoprene, etc.) which is connectedalong the circumference of hood 12 and frame 170 may be advanced and/orretracted through this annular channel 174.

With hood 12 expanded and frame 170 positioned within annular channel174, frame support member 172 may be tensioned or drawn proximally, asindicated in FIG. 11B, such that frame 170 is pulled proximally throughannular channel 174. As the frame may be made from a shape memory alloy,frame 170 is able to bend and conform itself into catheter 16, as shownin FIG. 11C, such that frame 170 is narrowed into an oval shape whenretracted, as indicated by the direction of collapse 176. To deploy hood12 and frame 170, the steps may be repeated in reverse such that hood 12is deployed with frame 170 advanced through channel 174 into positionwithin hood 12.

FIGS. 12A and 12B illustrate partial cross-sectional perspective viewsof hood 12 collapsed and fully retracted within catheter 16 once frame170 has been completely withdrawn from hood 12. FIGS. 13A and 13B showpartial cross-sectional side views of hood 12 withdrawn within catheter16 with frame 170 retracted corresponding to FIGS. 12A and 12B.

Further details of the visualization catheter and methods of use areshown and described in U.S. Pat. Pub. 2006/0184048 A1, which has beenincorporated herein above.

In yet other variations for providing structural strength to the hood inits expanded configuration, FIGS. 14A and 14B show side and perspectiveviews, respectively, of another variation utilizing an inflatable orexpandable hood 12 having circumferentially 180 and/or axially 182oriented structural linings or “ligaments” providing circumferential andaxial strength to the hood 12, respectively. Visualization element 184(e.g., CMOS imager, CCD imager, optical fiber, etc.) may be optionallypositioned within or along an interior of hood 12.

Circumferentially aligned ligaments 180 near or along the distal area ofhood 12 can be extended at least partially or fully circumferentially.The circumferential ligaments 180 may enable high pressure gas and/orfluid to be injected into or within the lining of hood 12 to reinforcethe circumferential or hoop strength near or at the distal wall of hood12 as the pressurized gas or fluid forms circumferentially arrangedchannels that act as “ring struts” similarly to circumferential frame170 described above. These ligaments 180 may increase the hood'sresistance to prevent circumferential collapse or from closing at thedistal end. Similarly, axial ligaments 182 extended along the axis ofhood 12 may also improve the strength of hood 12 along the axis.Increase in the hood's threshold for axial loads may be particularlyuseful when high push or pull forces are imparted upon hood 12 to engagea target tissue perpendicularly.

To facilitate use of the devices for any of the procedures describedherein, hood 12 may also be integrated with one or more angledprojections 190 extending distally from hood 12, as shown in FIG. 15.Once hood 12 is contacted against a tissue region, projections 190 maybe engaged into the tissue by rotating catheter shaft 16 to temporarilysecure the hood 12 against the tissue surface. Disengagement may beaccomplished by simply rotating catheter shaft 16 in the oppositedirection. Catheter shaft 16 may also additionally incorporate aguidewire exchange lumen 192 defined along catheter 16 proximally ofhood 12. Lumen 192 may allow for the rapid exchange of devices,including the catheter 16 and hood 12, during an interventionalprocedure when utilized with guidewire 17.

FIGS. 16A and 16B further demonstrate another variation of thevisualization catheter with a rapid exchange feature 200 located alonghood 12 being used with a guidewire 17 in the side and perspectiveviews, respectively. The presence of rapid exchange on the visualizationcatheter may also eliminate the need for lengthy guidewires to be usedwhen the catheter is first advanced into the patient via the inferiorvena cava at the thigh area. The rapid exchange feature 200 on the hood12 can also be used with a variety of other catheter based toolsincluding, but not limited to, graspers, fiberscopes, intravascularultrasound (IVUS), temperature sensors, PFO occlusion devices, etc.

FIGS. 17A and 17B illustrate side and perspective views, respectively,of a variation where an ablation probe 202 may be inserted through therapid exchange feature 200 along hood 12. With the ablation probeinserted into the hood 12 via rapid exchange, articulation of the distalend of the catheter, i.e., the hood 12, can be carried out with lessresistance because the flexibility of the catheter is not compromised(i.e. remains the same) when there are a fewer number of tools (or anabsence of tools) loaded through the work channel. Moreover,articulation of the ablation probe may also be improved when insertedvia rapid exchange because the ablation probe need not conform to thepathway of the catheter when inserted through the side port of the hood,subsequently eliminating additional resistance to articulate the distalend. Furthermore, additional tools can be inserted into the hood whenall the work channels of the visualization catheter are occupied orused.

In addition to a guidewire rapid exchange feature, FIGS. 18A and 18Bshow side and perspective views, respectively, of yet another variationof the visualization catheter where the rapid exchange side port 204 canbe defined along catheter 16 proximal to hood 12, as above, but for thedirect passage of an instrument, such as an ablation probe 202, ratherthan a guidewire 17. Such rapid exchange features, either for theexchange of guidewires or instruments themselves, may be utilized withany number of procedures. Particularly in the case of intravascularpuncture, access, ablation, and/or other treatments, etc. where theutilization of rapid exchange may be useful in facilitating suchprocedures.

The applications of the disclosed invention discussed above are notlimited to certain treatments or regions of the body, but may includeany number of other treatments and areas of the body. Modification ofthe above-described methods and devices for carrying out the invention,and variations of aspects of the invention that are obvious to those ofskill in the arts are intended to be within the scope of thisdisclosure. Moreover, various combinations of aspects between examplesare also contemplated and are considered to be within the scope of thisdisclosure as well.

What is claimed is:
 1. An apparatus for stabilizing an open area of avisualization catheter, comprising: a deployment catheter defining atleast one lumen therethrough; a barrier or membrane having an innerlayer and an outer layer projecting distally from the deploymentcatheter such that the inner layer defines the open area therein and theouter layer is positioned adjacent to the inner layer whereby the innerlayer and outer layer define an annular channel through the barrier ormembrane, wherein the open area is in fluid communication with the atleast one lumen and with an environment external to the barrier ormembrane; a collapsible frame having a low-profile configuration and anexpanded configuration which is advanceable through the annular channeldefined between the inner layer and outer layer of the barrier ormembrane such that the frame in its expanded configuration is seatedcircumferentially along the barrier or membrane; and a visualizationelement disposed within or adjacent to the barrier or membrane forvisualizing tissue adjacent to the open area.
 2. The apparatus of claim1 wherein the collapsible frame comprises a circumferential frame havinga low-profile oval configuration.
 3. The apparatus of claim 1 furthercomprising an anchor member coupled to the frame and passing through thedeployment catheter.
 4. The apparatus of claim 1 wherein the barrier ormembrane is collapsible into a low-profile configuration within thecatheter.
 5. The apparatus of claim 1 wherein the barrier or membranedefines a plurality of ligaments therealong.
 6. The apparatus of claim 5wherein the ligaments comprises circumferentially oriented ligaments. 7.The apparatus of claim 6 wherein the ligaments further comprise axiallyoriented ligaments.
 8. The apparatus of claim 1 wherein the barrier ormembrane defines an opening therealong through which a rapid exchangeelement is capable of being inserted.
 9. The apparatus of claim 1wherein the catheter defines an opening therealong proximal to thebarrier or membrane through which a rapid exchange element is capable ofbeing inserted.
 10. A method of stabilizing an open area of avisualization catheter, comprising: intravascularly deploying a barrieror membrane having an inner layer and an outer layer projecting distallyfrom a deployment catheter to an expanded configuration such that theinner layer defines an open area and the outer layer is positionedadjacent to the inner layer whereby the inner layer and outer layerdefine an annular channel through the barrier or membrane; advancing acollapsible frame through the annular channel defined between the innerlayer and outer layer from a low-profile configuration to an expandedconfiguration such that the frame is seated circumferentially along thebarrier or membrane; displacing an opaque fluid with a transparent fluidintroduced through the catheter such that the opaque fluid is displacedfrom the open area defined by the barrier or membrane and an underlyingtissue region and into an environment external to the barrier ormembrane; and visualizing the underlying tissue region through thetransparent fluid.
 11. The method of claim 10 wherein advancingcomprises deploying the frame from an oval low-profile configuration toan expanded circumferential configuration.
 12. The method of claim 10further comprising treating the underlying tissue region via a therapywhile visualizing the therapy.
 13. The method of claim 10 furthercomprising retracting the collapsible frame into the low-profileconfiguration.
 14. The method of claim 13 further comprising retractingthe barrier or membrane into a low-profile configuration.
 15. The methodof claim 10 wherein the barrier or membrane defines a plurality ofligaments therealong.
 16. The method of claim 15 wherein the ligamentscomprises circumferentially oriented ligaments.
 17. The method of claim16 wherein the ligaments further comprise axially oriented ligaments.18. The method of claim 10 wherein the barrier or membrane defines anopening therealong through which a rapid exchange element is capable ofbeing inserted.
 19. The method of claim 10 wherein the catheter definesan opening therealong proximal to the barrier or membrane through whicha rapid exchange element is capable of being inserted.